Fuel pump



March 26, 1929. H. JUNKERSY 1,706,785

FUEL PUMP Filed Feb. 24, 1927 Patented Mar. 26, 1929.

PATENT orrics.

nueo Jennies, or DESSAU, GERMANY.

FUEL BUMP.

Application filed' February 24,1927, Serial No. 170,693, and in Germany February 26, 1926.

My invention relates to fuel pumps which are especially adapted for use in connection with internal combustion engines, and more particularly to pumps in which the delivery is interrupted by connecting the space in front of the piston with a point of reduced pressure. I I

It is an object of my invention to provide a fuel pump in which a separate valve gear for controlling the delivery is dispensed with and the complicationand loss of power involved by the use of such "alve gear are eliminated. To this end I provide a pump with a piston controlled suction port in which delivery is interrupted by means of conduits such as grooves, passages and the like, which are controlled by the piston in such manner as to connect the pump space with the suction pipe at the'moment of interruption.

It is another objectof my invention to provide means for varyingthe delivery of the pump.

In the novel pump the drawbacks inherent in fuel pumps as heretofore designed are eliminated. Separate valve gear for controlling the delivery more especially in engines operated with solid injection must be very rugged, being required to rapidly open the regulating valve against the delivery pressure which is high as a rule and particularly so in pumps having mechanical injection. As compared with pumps possessing a separate outlet for the superfluous fuel, my pump is simpler and more reliable. If it is desired to regulate the delivery the cooperating edges at the piston or the corresponding conduit can be adjusted with respect to each other so as to vary the effective stroke of the piston.

In the drawings affixed to this specification and forming part thereof pumps embodying my invention are illustrated diagramamtically by way of example.

In the drawings:

Figs. 1 and 2 illustrate apump in which the excess of fuel is returned to the suction 7 line, the piston being shown at the outer and inner end of its stroke, respectively.

Fig. 3 is a longitudinal section of a pump provided with means for varying the delivery limit, I

Figs. 4, 5 and 6 are developments of the piston surface in this pump in various relative positions,

Fig. 7 is a section on the line VII-VII in Fig. 3.

all the'figures 1 is the piston, 2 is the cylinder, 3 is the suction port, 4 is the delivery valve, and 5 is the space or working chamber of the cylinder in front of the piston.

Referring first to Figs. 1 and 2, 6 is an axial bore in the piston, 7 are radial bores connecting the axial bore 6 with a circumferential groove 10 in the piston, and 11 is the controlling edge of this groove. Fuel is supplied to the pump during the suction stroke through the passage 3 as shown in i Fig. 1. On the return stroke of the piston the delivery of pump begins when the front face 8 of the piston has closed the suction passage 3 and delivery is continued until the edge 11 of the groove 10registers with the suction passage 3 so that it is connected with the space 5 by way of groove 10 and bores 6 and 7. The liquid in front of the piston is then discharged through the deliveryvalve 4 until the piston has reached its inner dead centre position as shown in Fig. 2. The piston is now reversed, drawing fuel into the space 5 through the suction passage 3, and a new cycle is started.

Instead of an axial bore 6 a longitudinal groove might be provided on the outer-face of the piston to connect the circumferential groove 10 with the space 5.

In the pump described delivery is interrupted only after its limit has been attained. Referring now to Figs. 3 to 7, these show a pump in which the means for interrupting the delivery are made adjustable and may be used for regulating the delivery. The piston is formed with two diametrically opposite reeesses 40 in its surface, each of which has a narrow port 41 extending to the front face 43 of the piston and 3, 3 are diametrically opposite suction passages, each adapted to cooperate with the controlling edge 42 of the corresponding recess. 45 is a lever splined on the piston which may be operated 100 by hand or by a governor so as to vary the relative position of the recesses 40 and the suction passages 3. Instead of the piston the cylinder, or both the piston and the cylinder, may be adjustable. Instead of two 105 suction passages and two recesses, a single suction passage and a single recess might be provided but the arrangement illustrated is preferable as transverse forces on the piston are balanced thereby.

The operation of this device will be better understood by reference to Figs. 4 to 6 where Figs. 4 and 5 illustrate the position of the piston for maximum delivery, Fig. 4 show ing the relative position of the recess 40 and the suction passage 3 at the beginning of the delivery stroke. In the position shown in Fig. 5 the.piston which is moving in the diretcion of the arrow is just going to lay open the suction passage 3 by its edge 42, and thus connecting the suction passage 3 with the space 5 through the port 41. Fig. 6 shows the piston adjusted for no delivery. In this case the passage 3 is opened by the edge 42 immediately after having been closed by the front face 43 of the piston. Intermediate positions of the lever 45 give deliveries intermediate nil and maximum.

Instead of the narrow port 41 a bore in the piston might be provided for connecting the space 5 with the recess or recesses 40 which might also be arranged in a reduced or enlarged portion of the piston, or in the cylinder.

It is a particular advantage of this device that any reaction on the governor is eliminated and that frictional resistance is practically nil. For, as the piston in operation moves in its longitudinal direction only, rotation of the piston at right angles to its reciprocation can be effected practically without resistance. Consequently the governor of an engine provided with such a pump can be very small whereby its arrangement is greatly facilitated.

As mentioned above, the passages 3 and the recesses 40 with their ports 41 may be arranged symmetrically with respect to the axis of the piston in order to avoid one-sided forces, as shown in Fig. 7. As a rule the recesses and bores are preferably distributed over the perimeter of the piston or cylinder so as to balance the upcoming forces. Such forces may arise in consequence of a pressure gradient in the vicinity of the openings of suction or interruption passages or the full pressure acting on one side of the piston, as

for instance, in the groove 40 if only one of such grooves is provided.

Instead of providing one pair of passages or the like disposed diametrically opposite each other, any number of passages may be provided and it is also possible to provide separate systerms of inoperative passages or the like to cooperate with the operatiye passages so as to balance the forces occurring from the latter passages.

I wish it to be understood that I do not desire to be ,limited'to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.

I claim 1. Fuel pump comprising a cylinder and a piston reciprocable in said cylinder, a valveless suction channel ending in the cylinder and adapted to be opened and closed by said piston, one of said parts being formed with a conduit freely ending at one end in the working chamber of the pump, the other end coinciding with the gliding surface of that part in which this conduit is formed, and adapted to be directly opened and closed in said piston for inter-ru ning the delivery, and one of said parts having at least one other passage communicating with the interior of said cylinder and ending in the side wall of said piston, this latter passage being so arranged that the lateral forces exerted on the piston by the liquid in the different channels, conduits and passages will balance each other.

2. A fuel pump comprising a cylinder and a piston movable therein, one of said parts having a system of passages communicating at least at one point with the working chamber of the pump and opening toward the gliding surface of the other part at points symmetrically related about said surface, whereby the side pressures which are exerted on the piston at these points by the reaction of the liquid balance each other, and a passage in the cylinder arranged to establish communication with parts of the said system of passageswhich open toward the gliding surface to thereby interrupt the delivery stroke and expel excess fuel from the working chamber.

8. A pump as claimed in claim 2 wherein one of the system of passages is provided with a controlling edge extending obliquely to the axis of the piston, combined with means for rotating the piston relative to the cylinder for regulating the quantity of fuel delivered.

4. A fuel pump comprising a cylinder and a piston movable therein, one of the said parts being provided with means establishing communication between the working chamber of the pump and the gliding surface of the piston at points thereabout capable of neutralizing side pressures on the piston, and a supply passage in the cylinder adapted to cooperate with said communicating means.

5. A fuel pump comprising a cylinder and a piston movable therein, one of the said parts being provided with means establishing communication between the working chamber of the pump and the gliding surface of the piston, and fuel supply means in the cylinder adapted to cooperate with said communicating means and opening toward the gliding surface of the piston at opposite points tending to equalize side pressures on the piston.

6. A fuel pump comprisin a cylinder and a piston movable therein, one of the said parts being provided. with means establishing communication between the working chamber of the pump and the glidingsur- 7. A pump as claimed in claim 6 wherein 1 face of the piston at points thereabout capathe communicating means includes a pluble of neutralizing side pressures on the pisrality of passages, each of which is provided ton, and fuel supply means in the cylinder with an obliquely extending control edge,

5 adapted to cooperate with said communicatcombined with means to vary the angular ing means and opening toward the gliding displacement of the piston relative to the 15 surface of the piston at opposing points tendcylinder. ing to also equalize side pressures on the In testimony whereof Iaflix my signature. piston. HUGO JUNKERS. 

